In designing integrated circuits using computer-aided design apparatus, a design engineer produces a schematic of the integrated circuit that is being designed by selecting specific devices or sub-circuits from a device library and inter-connecting the terminals of the devices or sub-circuits as required to form the schematic. The device library contains digital data for producing representations of common devices or sub-circuits. The devices and sub-circuits are categorized in the library by design parameters and/or operating characteristics. Selection of a device or sub-circuit from the device library causes a representation of the selected device or sub-circuit to be displayed on the screen of a display unit.
Different design methodologies are used in the design of integrated circuit memory devices depending upon the type of integrated circuit device that is being designed. For example, in designing dynamic random access memory (DRAM) devices, circuit designers generally specify logic gates of such circuits in terms of their drive strengths. However, in designing static random access memory (SRAM) devices, circuit designers generally specify components of such circuits in terms of device parameters, such as channel length and width for the field-effect transistors that form the integrated circuit memory. Because the two design methodologies are based on different hierarchies, two device libraries are required, one library for use in the design of DRAM type memory devices and a separate library for use in the design of SRAM type memory devices. In many cases, a circuit designer may have to access both libraries during the design process. The need to access two different device libraries makes the circuit design process less efficient.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art to be able to obtain logic gate drive strength and/or device parameters from a single cell library for use in creating a circuit schematic for an integrated circuit.